Solar energy, after hydropower and wind, is the third-largest renewable energy source. It has developed as a clean, sustainable, and powerful alternative to fossil fuels. The amount of sunshine reaching the Earth is more than 10,000 times the total energy used by the world, and technology to gather as much solar energy as possible is fast developing.
Since Bell Laboratories created the first commercial silicon (Si) solar panels in 1954, the most common technologies today use various sorts of Si-based solar cells to convert up to 20% of sunshine to power.
According to the IEA's market study, solar photovoltaics (PV) generation — the process of converting sunshine into energy — increased to 720 TWh in 2019 from 585 TWh in 2018, and is predicted to reach 1,940 TWh by 2025. Solar energy has a maximum capacity of 592 GW and contributes 2.2 percent to worldwide electricity output.
Current and Upcoming Materials
A typical solar cell consists of semiconducting materials such as p- and n-type silicon coupled to an external circuit through a stacked p-n junction. Electrons are ejected from silicon when the panels are illuminated by sunlight. Under the influence of an internal electric field, expelled electrons cause a current to flow via the p-n junction and the external circuit, resulting in a current (electricity).
R&D on novel solar energy materials is at an all-time high to achieve maximum sun-to-electricity efficiency at low cost, thanks to a rapidly rising industry and the creation of inventive applications. Today's highly explored semiconducting materials are crystalline Si, thin films, and next-generation materials.
Thin Films
Due to their narrow design (350 times smaller light-absorbing layers than typical Si-panels), lightweight, flexibility, and ease of installation, second-generation thin-film solar cells are emerging as one of the most promising PV technologies. Cadmium-telluride (CdTe), amorphous silicon, copper-indium-gallium-selenide (CIGS), and gallium-arsenide are the most common materials employed in their fabrication (GaAs).
While the toxicity of CdTe is a problem due to the cadmium, CIGS solar cells are emerging as the more promising high-efficiency and cost-effective alternative for both residential and commercial installations, with an efficiency of up to 21%.
Perovskite Solar Cells
Due to their low cost, thinner design, low-temperature processing, and excellent light absorption qualities, hybrid metal halide perovskite solar cells (PSCs) have gotten a lot of attention among next-generation solar cells (good performance under low and diffuse light). PSCs can be semitransparent, flexible, and lightweight. Perovskite thin films can also be printed, allowing for scalable high-throughput manufacturing, and a recent roll-to-roll printed PSC achieved the greatest efficiency among printed PSCs at 12.2 percent.
According to Oxford PV, integrated perovskite and Si-PV materials have exhibited a record efficiency of up to 28% in laboratory circumstances. While stability and durability have remained a serious worry, PSCs have recently been able to sustain ordinary working conditions thanks to a new low-cost polymer-glass stack encapsulation technology. Despite the fact that PSCs have yet to be commercialized, they have major economic and efficiency advantages that will drive the solar energy business forward in the future.
Solar Fabric
Solar radiation can be found all around the world, so why not use it to generate your own energy wherever it is needed? Consider the possibility that, in addition to creating solar power at a fixed site, you could also do so while moving around in your own clothes.
Solar textiles are being developed by researchers with the goal of incorporating solar power into each fiber. These solar filaments may be woven into t-shirts, winter jackets, or any other type of clothing to keep you warm, charge your phone, and supply energy for other requirements while you're out and about. Researchers have sought to combine solar fabric and solar panels in a number of areas, including:
- Building facades that are both a source of shade and a source of energy
- Awnings that illuminate streetlights and curtains that reduce grid power usage
- Household apparel made from solar panels might help you save money on solar panel mounting and installation.
Solar cell manufacturers are also working on the US Army initiative with the goal of developing solar-powered robotic tents. With solar costs lowering all the time, it's not hard to envisage a future when practically everything is powered by the sun for free.
Photovoltaic solar noise barriers (PVNB)
Highway traffic noise has traditionally been a source of worry in the United States. To address this problem, approximately 3,000 miles of traffic noise barriers have been constructed in 48 states. Noise barriers have always been built with the sole purpose of creating low-cost barriers that effectively execute noise abatement duties. However, the US Department of Energy's goal has recently shifted to combining noise reduction with long-term electricity generation.
Given the widespread use of noise barriers in the United States, the yearly solar energy production potential is estimated to be around 400 gigawatt-hours (GWh). This is roughly equivalent to the annual electricity consumption of 37,000 households.
Multi-junction solar cells
Solar cells with multiple junctions, commonly known as stacked cells, have higher efficiency than single-junction cells. Under laboratory circumstances, efficiencies of around 45 percent have been reached frequently. They appear to be promising additions to a clean energy revolution, and they are already finding commercial uses in space technology. Multi-functionals, on the other hand, are still quite expensive and not widely available for home use.
The fact that various semiconductive materials absorb solar radiation at different wavelengths is the basis for multi-junction PV cells. However, just stacking two, three, or more components is insufficient to make them operate together. They're usually too structurally dissimilar for that. So far, researchers have devised two methods for making stacked cells function. For one thing, they may form tunnel connections between the layers, allowing electrons to pass through.
Alternatively, they might utilize a variety of semiconductive materials that can easily chemically link together. The chemical links allow energy to circulate, making the materials electrically coupled. Using six multi-junctions, the highest multi-junction PV cell efficiency in the lab to date was 47.1 percent.
Conclusion
Solar energy was formerly only generated by ground-mounted or rooftop panels. However, as a result of all of the foregoing developments, solar is expected to become lighter, more flexible, and more widely applicable.
Imagine having access to all of this technology and traveling to a different city. You can buy food from a solar-powered food cart, eat it on a solar-powered roadway, and charge your phone with solar-powered clothing. This is how the near future appears!
There are also a slew of additional cutting-edge residential solar systems in the works or set to launch in 2021. Perovskite solar cells, which could soon be used to make solar paint, are perhaps the most promising new technology.